Liquid crystal droplets dispersed in thin films of UV-curable polymers

Abstract

Optically responsive films comprising birefringent nematic and/or birefringent chiral nematic liquid crystal microdroplets dispersed in UV-cured polymeric reaction products of di- and/or triallyl ethers and esters and suitable polythiols are disclosed.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 
     
       1. An optically responsive film comprising birefringent nematic and/or brirefringent chiral nematic liquid crystal microdroplets dispersed in a film of the ultraviolet radiation cured reaction product of a polyallyl compound and a polythiol taken from the group consisting of Z[OCO(CH 2 ) n  SH] m , where Z=a polyvalent organic moiety which is the CH 0-3  group containing nucleus of a tri- or tetravalent alcohol of the type of glycerol or pentaerythritol, m=3 or 4and n=1 to 5, said microdroplets displaying positive dielectric anisotropy and/or positive diamagnetic anisotropy, said film being capable of undergoing repeated thermally and electrically or magnetically induced transitions between opaque and transparent. 
     
     
       2. An optically responsive film comprising birefringent nematic and/or birefringent chiral nematic liquid crystal microdroplets dispersed in a film of the ultraviolet radiation cured reaction product of triallyl isocyanurate and pentaerythritol tetakis(3-mercapto-propionate), said microdroplets displaying positive dielectric anisotropy and/or positive diamagnetic anisotropy, said film being capable of undergoing repeated thermally and electrically or magnetically induced transitions between opaque and transparent. 
     
     
       3. A method of making an optically responsive film containing microdroplets of a birefringent nematic and/or birefringent chiral nematic liquid crystal material dispersed in a polymer film comprising mixing a liquid crystal material with the UV-curable liquid precursor mixture comprising a polyallyl compound and a polythiol taken from the group consisting of Z[OCO(CH 2 ) n  SH] m , where Z=a polyvalent organic moiety which is the CH 0-3  group containing nucleus of a tri- or tetravalent alcohol of the type of glycerol or pentaerythritol, m=3 or 4and n=1 to 5, and thereafter   curing the mixture in the form of a film with high intensity ultraviolet radiation to thereby form a cured polymer matrix which is a reaction product of said allyl compound and polythiol containing dispersed therein droplets of liquid crystal material displaying positive dielectric anisotropy and/or positive diamagnetic anisotropy.   
     
     
       4. A method of making an optically responsive film containing microdroplets of a birefringent nematic and/or birefringent chiral nematic liquid crystal material dispersed in a polymer film comprising mixing a liquid crystal material with the UV-curable liquid precursor mixture comprising triallyl isocyanurate and pentaerythritol tetrakis(3-mercapto-propionate) and thereafter   curing the mixture in the form of a film with high intensity ultraviolet radiation to thereby form a cured polymer matrix which is a reaction product of said precursors containing dispersed therein droplets of liquid crystal material displaying positive dielectric anistropy and/or positive diamagnetic anisotropy.